HOLY LONG OVERDUE UPDATE!!!

Well, life got in the way... (or boats did) and this project has been sitting a YEAR!!!

I finally feel a little better, as I definitely know now 100%, that the heads had to come off... Not solely a cylinder wash issue, but still certainly my primary suspect to the low compression... I started inspecting the heads, and it looks like about 1/2 of my exhaust valves are leaky... It turns out there was crap stuck to the valve seating area, which:
A- I have no idea what it is
B- I have no idea how to prevent it again...

Crap on the seat post here:
https://www.jaguarforums.com/forum/x...6/#post1191197

I'll repost pics here too...

Current theory is that water loss caused undetected overheat, causing debris to create leaky exhaust valves, which in turn caused lower compression, leading to cylinder wash causing major compression loss?????

Hundreds of cylinder pictures reveal that the low compression holes had no differences in cylinder wear... I'll take bore measurements, but it's pretty pointless, as I can see most of the cross hatch pattern in all areas of the bores...

My thought is to clean the clumps off the exhaust seats, touch up exhaust valve lap job (boy that sounded dirty) , recheck the decks, oil up the bores and slap this baby back together...

Any opinions???

As always... THANK YOU for lookin'!!!
HS

 

Had the heads checked out at a reputable machine shop...

Pressure tested = no cracks

Decks were perfecto...

Off to check the block decks, and gauge the bores!

 

It may be just a time to go issue! I picked up my '99 with 155k on the clock today after a head gasket failure. I was driving, enjoying the day, car running great, then rough and then white smoke. I had my shop do the head gasket (beyond my skill) and did several other tasks while the head was off (now have heat!, hose bent to far) new vacuum line to brake booster. Let's say $4,500 usd later I am driving. My story was "white smoke" in the thread.

 

I've had enough cars to agree with you... sometimes they just go with a little unknown nudge... Last one like this was an XJ6 I had... same story as yours...

 

Cruising along steadily now....

Block decks are also flatter than the earth in old world maps... I can't fit an 0.002" feeler in any orientation...

Bores get checked today... but as mentioned, cross hatch visible most places... I expect some wear, but well within tolerance limits...

Valves are touched up with a lap job, ready to put back together...